load balancing on one interface

[Gustavo]

Hi list !
I am trying to make a balancing of 2 links DSL in one inteface,
I used the following rule to make the balancing:
# rules
pass in on $if_lan route-to \
      { ( $if_adsl $gw1 ), ( $if_adsl $gw2 ) } round-robin \
      from $rede_lan to ! $rede_ipturbo keep state
mine it doubts is in the out rule of of links, as i could specifies them 
in one same interface?

pass out on $if_adsl route-to ($if_adsl $gw2) from $if_adsl \
 to any
pass out on $if_adsl route-to ($if_adsl $gw1) from $if_adsl \
 to any
Thankz
Gustavo